Abstract: The preferred embodiment of the present invention provides a novel method of forming MOS devices using hydrogen annealing. The method includes providing a semiconductor substrate including a first region and a second region, forming at least a portion of a first MOS device covering at least a portion of the first active region, performing a hydrogen annealing in an ambient containing substantially pure hydrogen on the semiconductor substrate. The hydrogen annealing is performed after the step of the at least a portion of the first MOS device is formed, and preferably after a pre-oxidation cleaning. The method further includes forming a second MOS device in the second active region after hydrogen annealing. The hydrogen annealing causes the surface of the second active region to be substantially rounded, while the surface of the first active region is substantially flat.